The invention concerns a rotor for impactors comprising a plurality of cast steel rotor discs which are welded together at their widened touching hubs and featuring a widened outer rim which, compared with the hub is half as wide on both sides to provide the space necessary between adjacent outer rims to allow for insertion of a welding tool through to the hubs, and the outer rims of the rotor discs are interrupted by peripheral recesses in all rotor discs arranged in alignment with one another to form blow bar holders.
Such a rotor is known from U.S. Pat. No. 5,392,999, whereby U.S. Pat. No. 5,381,973 shows a further embodiment of this rotor in respect of the welding together of the rotor discs at their hubs.
As the first of the above documents in particular shows, the rotor is used in conjunction with blow bars which are pressed by wedges against supporting bodies and by means of ribs provided thereon together with corresponding grooves in the bars are thus secured against radial movement outwards resulting from centrifugal force. In this known rotor, the wedges are manipulated by hydraulic pressure elements and retained in the clamped position as described in U.S. Pat. No. 5,221,059. Blow bar changing is effected by releasing the wedges and withdrawing or pushing the blow bars axially from their holders, or also by removing the wedges and removing the blow bars radially from out of the peripheral recesses, for which purpose the rotor has to be rotated into such a position that the blow bar to be removed lies flat on its back. To do this, however, it must be lifted over the supporting body ribs, which are also designated as blow bar holder. The fitting of a new or even a turned blow bar is effected in the reverse sequence.
A rotor with hydraulic pressure elements is expensive and also susceptible to breakdown. Furthermore, the blow bars in the known rotor are not vertically removable, i.e. cannot be taken out from the top, since due to their extreme weight there are problems during removal of the wedges, also the pressure elements and the pressure line rails carrying them can be damaged.
Mechanically manipulated pressure elements like those known, for example, from DE-GM 80 12 521 and DE-GM 85 20 900, cannot be used with rotors of the generic type, since the widened outer rims do not allow access for such parts, in particular tools required for the tightening or loosening of such parts. Sometimes, mechanical pressure elements and their screw spindles or similar need to be removed by flame cutting. Such lack of accessibility is valid in particular to small and medium-sized rotors where, for cost reasons, mechanical pressure elements and retaining pieces respectively are needed specifically for those sizes.